/* -------------------------------------------------------------------------
 *
 * pg_list.h
 *	  interface for openGauss generic linked list package
 *
 * This package implements singly-linked homogeneous lists.
 *
 * It is important to have constant-time length, append, and prepend
 * operations. To achieve this, we deal with two distinct data
 * structures:
 *
 *		1. A set of "list cells": each cell contains a data field and
 *		   a link to the next cell in the list or NULL.
 *		2. A single structure containing metadata about the list: the
 *		   type of the list, pointers to the head and tail cells, and
 *		   the length of the list.
 *
 * We support three types of lists:
 *
 *	T_List: lists of pointers
 *		(in practice usually pointers to Nodes, but not always;
 *		declared as "void *" to minimize casting annoyances)
 *	T_IntList: lists of integers
 *	T_OidList: lists of Oids
 *
 * (At the moment, ints and Oids are the same size, but they may not
 * always be so; try to be careful to maintain the distinction.)
 *
 *
 * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/nodes/pg_list.h
 *
 * -------------------------------------------------------------------------
 */
#ifndef PG_LIST_H
#define PG_LIST_H

#include "nodes/nodes.h"

typedef struct ListCell ListCell;

typedef struct DListCell DListCell;

typedef struct List {
    NodeTag type; /* T_List, T_IntList, or T_OidList */
    int length;
    ListCell* head;
    ListCell* tail;
} List;

struct ListCell {
    union {
        void* ptr_value;
        int int_value;
        Oid oid_value;
    } data;
    ListCell* next;
};

typedef struct DList {
    NodeTag type;
    int length;
    DListCell* head;
    DListCell* tail;
} DList;

struct DListCell {
    union {
        void* ptr_value;
        int int_value;
        Oid oid_value;
    } data;
    DListCell* next;
    DListCell* prev;
};

/*
 * The *only* valid representation of an empty list is NIL; in other
 * words, a non-NIL list is guaranteed to have length >= 1 and
 * head/tail != NULL
 */
#define NIL ((List*)NULL)

/*
 * These routines are used frequently. However, we can't implement
 * them as macros, since we want to avoid double-evaluation of macro
 * arguments. Therefore, we implement them using static inline functions
 * if supported by the compiler, or as regular functions otherwise.
 */
#ifdef USE_INLINE

static inline ListCell* list_head(const List* l)
{
    return l ? l->head : NULL;
}

static inline ListCell* list_tail(const List* l)
{
    return l ? l->tail : NULL;
}

static inline int list_length(const List* l)
{
    return l ? l->length : 0;
}

static inline DListCell* dlist_head_cell(const DList* l)
{
    return l ? l->head : NULL;
}

static inline DListCell* dlist_tail_cell(DList* l)
{
    return l ? l->tail : NULL;
}

#else

extern ListCell* list_head(const List* l);
extern ListCell* list_tail(List* l);
extern int list_length(const List* l);

extern ListCell *dlist_head_cell(const DList *l);
extern ListCell *dlist_tail_cell(DList *l);

#endif /* USE_INLINE */

/*
 * NB: There is an unfortunate legacy from a previous incarnation of
 * the List API: the macro lfirst() was used to mean "the data in this
 * cons cell". To avoid changing every usage of lfirst(), that meaning
 * has been kept. As a result, lfirst() takes a ListCell and returns
 * the data it contains; to get the data in the first cell of a
 * List, use linitial(). Worse, lsecond() is more closely related to
 * linitial() than lfirst(): given a List, lsecond() returns the data
 * in the second cons cell.
 */
#define lnext(lc) ((lc)->next)
#define lprev(lc) ((lc)->prev)
#define lfirst(lc) ((lc)->data.ptr_value)
#define lfirst_int(lc) ((lc)->data.int_value)
#define lfirst_oid(lc) ((lc)->data.oid_value)
#define lfirst_node(type, lc) castNode(type, lfirst(lc))

#define linitial(l) lfirst(list_head(l))
#define linitial2(l) (l ? lfirst(list_head(l)) : 0)
#define linitial_int(l) lfirst_int(list_head(l))
#define linitial2_int(l) (l ? lfirst_int(list_head(l)) : 0)
#define linitial_oid(l) lfirst_oid(list_head(l))
#define linitial_node(type, l) castNode(type, linitial(l))

#define lsecond(l) lfirst(lnext(list_head(l)))
#define lsecond_int(l) lfirst_int(lnext(list_head(l)))
#define lsecond_oid(l) lfirst_oid(lnext(list_head(l)))
#define lsecond_node(type, l) castNode(type, lsecond(l))

#define lthird(l) lfirst(lnext(lnext(list_head(l))))
#define lthird_int(l) lfirst_int(lnext(lnext(list_head(l))))
#define lthird_oid(l) lfirst_oid(lnext(lnext(list_head(l))))
#define lthird_node(type, l) castNode(type, lthird(l))

#define lfourth(l) lfirst(lnext(lnext(lnext(list_head(l)))))
#define lfourth_int(l) lfirst_int(lnext(lnext(lnext(list_head(l)))))
#define lfourth_oid(l) lfirst_oid(lnext(lnext(lnext(list_head(l)))))
#define lfourth_node(type, l) castNode(type, lfourth(l))

#define llast(l) lfirst(list_tail(l))
#define llast_int(l) lfirst_int(list_tail(l))
#define llast_oid(l) lfirst_oid(list_tail(l))
#define llast_node(type, l) castNode(type, llast(l))

/*
 * Convenience macros for building fixed-length lists
 */
#define list_make1(x1) lcons(x1, NIL)
#define list_make2(x1, x2) lcons(x1, list_make1(x2))
#define list_make3(x1, x2, x3) lcons(x1, list_make2(x2, x3))
#define list_make4(x1, x2, x3, x4) lcons(x1, list_make3(x2, x3, x4))

#define list_make1_int(x1) lcons_int(x1, NIL)
#define list_make2_int(x1, x2) lcons_int(x1, list_make1_int(x2))
#define list_make3_int(x1, x2, x3) lcons_int(x1, list_make2_int(x2, x3))
#define list_make4_int(x1, x2, x3, x4) lcons_int(x1, list_make3_int(x2, x3, x4))

#define list_make1_oid(x1) lcons_oid(x1, NIL)
#define list_make2_oid(x1, x2) lcons_oid(x1, list_make1_oid(x2))
#define list_make3_oid(x1, x2, x3) lcons_oid(x1, list_make2_oid(x2, x3))
#define list_make4_oid(x1, x2, x3, x4) lcons_oid(x1, list_make3_oid(x2, x3, x4))

/*
 * foreach -
 *	  a convenience macro which loops through the list
 */
#define foreach(cell, l) for ((cell) = list_head(l); (cell) != NULL; (cell) = lnext(cell))

#define foreach_cell(cell, l) for (ListCell* cell = list_head(l); cell != NULL; cell = lnext(cell))

#define dlist_foreach_cell(cell, l)    \
    for ((cell) = dlist_head_cell(l); (cell) != NULL; (cell) = lnext(cell))

/*
 * for_each_cell -
 *	  a convenience macro which loops through a list starting from a
 *	  specified cell
 */
#define for_each_cell(cell, initcell) for ((cell) = (initcell); (cell) != NULL; (cell) = lnext(cell))

/*
 * forboth -
 *	  a convenience macro for advancing through two linked lists
 *	  simultaneously. This macro loops through both lists at the same
 *	  time, stopping when either list runs out of elements. Depending
 *	  on the requirements of the call site, it may also be wise to
 *	  assert that the lengths of the two lists are equal.
 */
#define forboth(cell1, list1, cell2, list2)                                                          \
    for ((cell1) = list_head(list1), (cell2) = list_head(list2); (cell1) != NULL && (cell2) != NULL; \
         (cell1) = lnext(cell1), (cell2) = lnext(cell2))

/*
 * forthree -
 *	  the same for three lists
 */
#define forthree(cell1, list1, cell2, list2, cell3, list3)                                   \
    for ((cell1) = list_head(list1), (cell2) = list_head(list2), (cell3) = list_head(list3); \
         (cell1) != NULL && (cell2) != NULL && (cell3) != NULL;                              \
         (cell1) = lnext(cell1), (cell2) = lnext(cell2), (cell3) = lnext(cell3))

#define forfour(cell1, list1, cell2, list2, cell3, list3,  cell4, list4)                                   \
    for ((cell1) = list_head(list1), (cell2) = list_head(list2), (cell3) = list_head(list3), (cell4) = list_head(list4); \
         (cell1) != NULL && (cell2) != NULL && (cell3) != NULL && (cell4) != NULL;                              \
         (cell1) = lnext(cell1), (cell2) = lnext(cell2), (cell3) = lnext(cell3), (cell4) = lnext(cell4))


extern DList* dlappend(DList* dlist, void* datum);

extern List* lappend(List* list, void* datum);
extern List* lappend2(List* list, ListCell* cell);
extern List* lappend3(List*, List*);
extern List* lappend_int(List* list, int datum);
extern List* lappend_oid(List* list, Oid datum);

extern ListCell* lappend_cell(List* list, ListCell* prev, void* datum);
extern ListCell* lappend_cell_int(List* list, ListCell* prev, int datum);
extern ListCell* lappend_cell_oid(List* list, ListCell* prev, Oid datum);

extern List* lcons(void* datum, List* list);
extern List* lcons_int(int datum, List* list);
extern List* lcons_oid(Oid datum, List* list);

extern List* list_concat(List* list1, List* list2);
extern List* list_concat2(List* list1, List* list2);
extern List* list_truncate(List* list, int new_size);

extern void* list_nth(const List* list, int n);
extern ListCell* list_nth_cell(const List* list, int n);
extern int list_nth_int(const List* list, int n);
extern Oid list_nth_oid(const List* list, int n);
#define list_nth_node(type, list, n) castNode(type, list_nth(list, n))

extern bool list_member(const List* list, const void* datum);
extern bool list_member_ptr(const List* list, const void* datum);
extern bool list_member_int(const List* list, int datum);
extern bool list_member_oid(const List* list, Oid datum);

extern List* list_delete(List* list, const void* datum);
extern List* list_delete_ptr(List* list, const void* datum);
extern List* list_delete_int(List* list, int datum);
extern List* list_delete_oid(List* list, Oid datum);
extern List* list_delete_first(List* list);
extern List* list_delete_first_nofree(List* list);
extern List* list_delete_cell(List* list, ListCell* cell, ListCell* prev);
extern List* list_delete_cell2(List* list, ListCell* cell);
extern List *list_delete_name(List *list, const char* name);

extern DList* dlist_delete_cell(DList* dlist, DListCell* cell, bool deep);

extern List* RemoveListCell(List* list, int pos);

typedef bool (*NodeMatchFunc)(void* val1, void* val2);
typedef void (*NodeHandler)(void*);
extern List* list_cell_clear(List* list, void* val, NodeMatchFunc is_match);
extern List* list_cell_handle(List* list, NodeHandler handle, bool removed);

extern List* list_union(const List* list1, const List* list2);
extern List* list_union_ptr(const List* list1, const List* list2);
extern List* list_union_int(const List* list1, const List* list2);
extern List* list_union_oid(const List* list1, const List* list2);
extern List* list_intersection_int(const List* list1, const List* list2);
extern bool list_is_subset(List* list1, List* list2);
extern bool list_is_subset_int(List* list1, List* list2);

#ifdef PGXC
/* Well... this is used by Postgres-XC */
extern List* list_intersection_int(const List* list1, const List* list2);
#endif
extern List* list_intersection(const List* list1, const List* list2);

/* currently, there's no need for list_intersection_int etc */
extern List* list_difference(const List* list1, const List* list2);
extern List* list_difference_ptr(const List* list1, const List* list2);
extern List* list_difference_int(const List* list1, const List* list2);
extern List* list_difference_oid(const List* list1, const List* list2);

extern List* list_append_unique(List* list, void* datum);
extern List* list_append_unique_ptr(List* list, void* datum);
extern List* list_append_unique_int(List* list, int datum);
extern List* list_append_unique_oid(List* list, Oid datum);

extern List* list_concat_unique(List* list1, List* list2);
extern List* list_concat_unique_ptr(List* list1, List* list2);
extern List* list_concat_unique_int(List* list1, List* list2);
extern List* list_concat_unique_oid(List* list1, List* list2);

extern void dlist_free(DList* list, bool deep);

extern void list_free(List* list);
extern void list_free_deep(List* list);

#define list_free_ext(list)  \
    do {                     \
        if ((list) != NIL) { \
            list_free(list); \
            list = NIL;      \
        }                    \
    } while (0)

extern List* list_copy(const List* list);
extern List* list_copy_tail(const List* list, int nskip);

extern void dlist_add_tail_cell(DList* dlist, DListCell* cell);
extern List* list_merge_int(List* list1, List* list2);
extern List* list_insert_nth_oid(List *list, int pos, Oid datum);

/*
 * To ease migration to the new list API, a set of compatibility
 * macros are provided that reduce the impact of the list API changes
 * as far as possible. Until client code has been rewritten to use the
 * new list API, the ENABLE_LIST_COMPAT symbol can be defined before
 * including pg_list.h
 */
#ifdef ENABLE_LIST_COMPAT

#define lfirsti(lc) lfirst_int(lc)
#define lfirsto(lc) lfirst_oid(lc)

#define makeList1(x1) list_make1(x1)
#define makeList2(x1, x2) list_make2(x1, x2)
#define makeList3(x1, x2, x3) list_make3(x1, x2, x3)
#define makeList4(x1, x2, x3, x4) list_make4(x1, x2, x3, x4)

#define makeListi1(x1) list_make1_int(x1)
#define makeListi2(x1, x2) list_make2_int(x1, x2)

#define makeListo1(x1) list_make1_oid(x1)
#define makeListo2(x1, x2) list_make2_oid(x1, x2)

#define lconsi(datum, list) lcons_int(datum, list)
#define lconso(datum, list) lcons_oid(datum, list)

#define lappendi(list, datum) lappend_int(list, datum)
#define lappendo(list, datum) lappend_oid(list, datum)

#define nconc(l1, l2) list_concat(l1, l2)

#define nth(n, list) list_nth(list, n)

#define member(datum, list) list_member(list, datum)
#define ptrMember(datum, list) list_member_ptr(list, datum)
#define intMember(datum, list) list_member_int(list, datum)
#define oidMember(datum, list) list_member_oid(list, datum)

/*
 * Note that the old lremove() determined equality via pointer
 * comparison, whereas the new list_delete() uses equal(); in order to
 * keep the same behavior, we therefore need to map lremove() calls to
 * list_delete_ptr() rather than list_delete()
 */
#define lremove(elem, list) list_delete_ptr(list, elem)
#define LispRemove(elem, list) list_delete(list, elem)
#define lremovei(elem, list) list_delete_int(list, elem)
#define lremoveo(elem, list) list_delete_oid(list, elem)

#define ltruncate(n, list) list_truncate(list, n)

#define set_union(l1, l2) list_union(l1, l2)
#define set_uniono(l1, l2) list_union_oid(l1, l2)
#define set_ptrUnion(l1, l2) list_union_ptr(l1, l2)

#define set_difference(l1, l2) list_difference(l1, l2)
#define set_differenceo(l1, l2) list_difference_oid(l1, l2)
#define set_ptrDifference(l1, l2) list_difference_ptr(l1, l2)

#define equali(l1, l2) equal(l1, l2)
#define equalo(l1, l2) equal(l1, l2)

#define freeList(list) list_free(list)

#define listCopy(list) list_copy(list)


/*
 * foreach_delete_current -
 * delete the current list element from the List associated with a
 * surrounding foreach() loop, returning the new List pointer.
 *
 * This is equivalent to list_delete_cell(), but it also adjusts the foreach
 * loop's state so that no list elements will be missed.  Do not delete
 * elements from an active foreach loop's list in any other way!
 */
#define foreach_delete_current(lst, cell)  \
    (cell##__state.i--,                    \
     (List *) (cell##__state.l = list_delete_cell(lst, cell)))


extern int length(List* list);
#endif /* ENABLE_LIST_COMPAT */

extern int dlength(DList* list);

#endif /* PG_LIST_H */
